Supplemental Information On Oil And Gas Exploration And Production Activities - Schedule Of Changes In Standardized Measure Of Discontinued Future Net Cash Flows Relating To Proved Oil And Natural Gas Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Extractive Industries [Abstract]
Standardized Measure, beginning of year	$ 255,856	$ 125,357	$ 25,132
Sales of oil and gas produced, net of production costs	(29,152)	(35,794)	(20,287)
Sales of minerals in place	(2,470)		(380)
Net changes in prices and production costs	(288,064)	(34,681)	241
Extensions, discoveries, and improved recoveries	6,514	54,157	48,006
Changes in income taxes, net	88,944	(88,944)
Previously estimated development costs incurred during the period	26,977	18,252	3,227
Net changes in future development costs	6,697	7,028	(22,966)
Purchases of minerals in place	7,695	163,309	56,069
Revisions of previous quantity estimates	(16,671)	16,283	26,259
Accretion of discount	25,586	12,536	2,513
Changes in timing of estimated cash flows and other	22,484	18,353	7,543
Standardized Measure, end of year	$ 104,396	$ 255,856	$ 125,357